This post is taken from the newsletter ” Human warmth “, sent every Tuesday at 12 noon. Every week, journalist Nabil Wakim, who hosts the Chaleur Humaine podcast, answers questions from Internet users about the climate challenge. You can register for free here:
“Hello, seeing the battle around water and mega basins, I don’t understand why we can’t desalinate seawater on a large scale, since some countries are already doing it? Is it a problem of technology to which we do not have access? » Question posed by Yves to the address [email protected]
My answer : Yes, we can absolutely desalinate seawater, and some countries like Saudi Arabia do it massively. But this poses three problems: it is very expensive, it risks generating additional greenhouse gas emissions and increasing pollution.
1 – Desalinated water costs an arm (of sea)
To get rid of salt, you have to use a process called reverse osmosis: fresh water is separated from salt water by a membrane. This requires very strong pressure for the water to pass through the membrane and leave the salt behind. The problem with this technology, which is very well known (including by French groups like Veolia or Suez), is that it requires a lot of energy. This is why it is widely used in countries that have access to inexpensive oil, notably Saudi Arabia, the United Arab Emirates or Oman – the Middle East accounts for around 50% of desalination capacity in the world. But in a country like France – which imports almost all of its oil and gas – fossil fuels are expensive and are likely to become more and more expensive in the future.
Over the past twenty years, significant efficiency efforts have been made and the construction of very large factories has made it possible to reduce costs somewhat in the Arabian Peninsula. But that doesn’t take anything away from the other problem: almost all of these factories run on fossil fuels, and this increase in energy consumption directly contributes to global warming… which itself causes an increase in droughts. . We cannot say that it is a completely virtuous circle.
(There is a great IFRI report on this subjectco-written by Marc-Antoine Eyl-Mazzega, who was one of the first guests on the Chaleur Humaine podcast to talk about Russian gas)
2 – Poorly measured pollution but with significant effects
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